Apparatus for purging refrigerating systems



Feb.1 1925- T. SHIPLELY URGING REFRIGERATING SYSTEMS APPARATUS FOR P Filed Feb. 6, 1924 Patented Feb. 3, 1925.

THOMAS SHIPLEY, OF YORK, EPENNSYLVANIA.

APPARATUS FOR PURGING REFRIGERATING SYSTEMS.

Application filed February 6, 1924. Serial No. 691,058.

Pennsylvania, have invented certain new and useful Improvements in Apparatus for Purging Refrigerating Systems, of which the following is a specification.

This invention relates to apparatusfor removing foreign gases from refrigerating systems and operates according to the method described and claimed in my copending application, Ser. No, 691,057 filed February 6, 1924.

The general principle of operation involves a recognition of the fact that the foreign gases, such as air, gases generated by the effect of heat on lubricating oil, etc, are, heavier than most gaseous refrigerants, and particularly anhydrous ammonia. This fact has not generally been understood for the reason that foreign gases have almost invariably tended to accumulate in the condenser which is usually at the highest part of the system.- This fact has led to the erroneous assumption.that the foreign gases are lighter than the ammonia gas. I have discovered that such gases remain in the upper part of the svstem because their outflow is precluded by liquid seals or traps formed by the liquid refrigerant either in the lower coils of the condenser or in the discharge header connections, or both.

The present invention involves the construction and operation of the condenser in such manner that the liquid refrigerant is not permitted to form a liquid seal or trap. I' then provide in the passage from the condenser to the receiver, a purge drum or foreign gas accumulator, and a liquid trap arranged in the order stated. The liquid trap may, and preferably does, also serve as a gravity oil separating trap.

The purge drum thus serves to accumulate the foreign gases held back by the trap and when these gases have accumulated in sufficient quantity the drum is cut out of the system and vented to the atmosphere.

As a refinement, I provide means by which I may chill the contents of the purge drum prior to venting it and after it has been out out of the system, the effect of such chilling being to liquefy substantially all the gaseous refrigerant while leaving the foreign gases in their gaseous condition. The refrigerant thus liquefied is then withdrawn from the purge drum and returned to the system after which the foreign gases freed of practically all refrigerant are vented to the atmosphere.

A preferred embodiment of the invention is illustrated in the accompanying drawing in diagrammatic elevation.

A portion of the condenser is shown at 1, the inlet or gas header at 2, the outlet or liquid header at 3, and a thermometer inserted in a thermometer well in the liquid header at 4. 'This condenser is shown as of the familiar atmospheric type and ordinarily would be provided vwith the usual water cooling sprays, not shown. The type of condenser is immaterial so long as it is so constructed or so operated that the liquid refrigerant does not form a liquid trap or seal either in the lower coils of the condenser or in the liquid header 3.

As explained, such a trap or seal confines the foreign gases to the condenser by preventing their escape therefrom in substantialquantity, and therefore causes, in the conventional type of system, the accumulation of foreign gases in the condenser and particularly in the upper portion thereof.

The liquid refrigerant line 5 leads downward through a branch 6 controlled by a valve 7 tothe so-called purge drum 8, the connection entering the top of the drum. The outlet connection 9 from the bottom of the drum 8 is controlled by a valve 10 and leads by way of the pipe 11 to the gravity oil trap 12. g

A by-pass 13 controlled by a valve 14 serves to establish a connection between the pipe 5 and the pipe 11. Normally the valve 14 is closed and the valves 7 and 10 are open so that liquid ammonia passing from the condenser 1 flows through the purge drum 8, and thence by way of the pipe 11 to the oil trap 12.- When the purge drum is to be freed of foreign gases, the valves 7 and 10 are closed to cut the drum 8 oft" from the system, and the valve 14 is opened to establish a bypass connection through which the plant is kept in operation during the venting of the purge drum.

The oil trap 12 is of familiar form and is provided with a gauge glass 15 to permit the operator to observe the level of on in the trap. The oil may be drawn off from time to time through the valve connection 16. The top of the trap 12 is connected. by

a pipe 17, controlled by a valve 18 with the liquid refrigerant receiver 19. The dlscharge of ammonia from the receiver 19 to the expansion coils, or other apparatus, 15 6 controlled by the valve 20. The valved connection 21 is a charging connection through which the system may be charged with refrigerant.

An equalizing pipe 22 is connected 1 through a valve 23 with the top of the trap 12, and through a valve 24 with the so called equalizing header 25. The header 25 is connected through valves 26 with the various coils making 11 the condenser (only one 0011 is visible in t e drawin The valve 27 offers means by whichthe condenser C01lS may be purged from the top, as is now the practice, in the event thatit should ever be desired to perform this operation.

The valves 23, 24, and 26 are normally 0 en, and the valve 27 is normally closed. The equalizing pipe 22 and header 'thus serve toe ualize the gas pressure at the top of the con enser with the gas pressure at the 25 top of the oil trap so that the oil and liquid 'ammonia may never be forced out of the trap and so that the trap will always serve to form a liquid seal controlling the discharge from the purge drum 8.

The apparatus so far described can be operated to purge the system, provided the purge drum be provided with a normally closed valve controlled vent. The operation is simply to close the valves 7 and-10 and I open the valve 14 to permit the'pla-nt to continue in operation, after which. the drum 8 is vented to the atmosphere. This discharges a mixture of ammonia and foreign gases but is quite an effective method because the foreign gases in the system tend to accumulate in the drum. The loss of refrigerant gas in any appreciable quantity is, however, unnecessary and my method is capable of being practiced in more refined 4 ,ways which virtually prevent this loss.

The drum 8 is provided with a pressure gauge 28 and may, if desired, also be equipped with a thermometer and well 29.

An expansion valve 30 is connected to re- (-eive liquid refrigerant from the receiver 19 (this connection is not shown in the drawing liquid refrigerant to expand into a .coil 31 housed within the purge drum 8.

The discharge 32 from the coil 31 is connected to the suction or low pressure line. hence the coil 31 acts as a refrigerating coil to chill the mixture of gases in the drum 8.

Its effect is to liquefy the ammonia gas while C3 leaving the foreign gases in their gaseous condition.

A valve 33 controls a passage to a socalled condensate indicator drum 34. This has a gauge glass 35 which permits the oporator to determine the level of the liquid The expansion valve 30 allows the ammonia in drum 34 as hereafter explained. A valve 36 controls a discharge connection leading from the bottom of the indicator drum 34 to the low pressure line or suction line of the system. It is the means used to restore the refrigerant liquefied in the purge drum to the system.

The purge drum 8 is connected by an equalizing pipe 37- controlledby a valve 38, with thetop of the indicator drum 34; pipe 37 serving as a ressure equalizing connection to permit t e free flow of liquid ammonia from the drum 8 to the drum 34, when the valves 33 and 38 are open. The valve 39 controls a vent or purge connection for both the drums 8 and 34.

When the engineer notes that the thermometer4 on the liquid header 3 indicates a temperature lower than that corresponding to the pressure shown by the high pressure gauge on the system, he knows that for eign gases are present. To remove such gases, he performs one or more purging operations on the drum 8.

The normal condition of the apparatus is as follows: valve 14 closed; valves 7 and 10 open; expansion valve 30 closed; vent valve 39 closed; liquid ammonia controlling valve 33 closed; equalizing valve'38 closed;

and liquid ammonia return valve 36 closed.

Each purging operation preferably consists of the following steps: valves 7 and 10.are closed and valve 14 is opened. This cuts the drum 8 out of the system and affords a by-pass around it. Expansion valve 30 is then opened to permit refrigerant to expand into the coil-31 and immediately thereafter the liquid ammonia control valve 33 and equalizing valve 38 are opened to 'drain liquefied ammonia from the drum 8 into the condensate indicator drum 34.

The desired liquefaction of the ammonia gas is indicated in two ways. During the chilling operation the gauge 28 will show a fall of pressure which will cease when liquefaction of the refrigerant has terminated. This condition will also be indicated by constant level of the liquefied ammonia in gauge glass 35. Absolutely complete liquefaction does noti'occur as is obvious from a consideration of the law of partial pressures.

When liquefaction is' accomplished as above described, the operator closes the valves 33 and 38 and opens the valve 36, permitting the liquid ammonia to flow to the low pressure line or suction line of the system thus recovering the liquid ammonia. When all the liquidammonia has been drawn 011', the valve 36 is closed.

The refrigerant now having been liquefied and recovered, expansion valve 30 is closed and valve 39 is opened to vent the purge drum 8.

Upon the completion of the venting, the valve 39 is closed, valves 7 and 10 are then opened. and valve 14 closed. In this way the purge drum 8 is restored as a part of the circulating system and commences once more to perform its function of accumulating foreign gases flowing from the condenser.

A purging apparatus which will operate to discharge foreign gases with only a very slight loss of refrigerant can be constructed by using a purge drum 8 with the refrigerating coil 31 and omitting the indicator drum 34 and its connections. With'such a device, after the valves 7 and 10 have been closed and the valve 14 opened,- the expansion valve 30 is opened and the contents of the drum 8 are chilled substantially below the temperature necessary to produce liquefaction of the refrigerant. The gauge 28 and thermometer 29 are helpful in performing this operation.

When the drum 8 has been sufiiciently chilled the valve 39 is opened for a short period and the effect is to permit the escape of foreign gases before vaporization of the liquid ammonia can occur in any substantial quantity.

While I contemplate the progressive ac-.

culnulation ofsuch gases in the drum 8, it is not strictly necessary hat the flow of foreign gases from the condenser 1 be continuous. It might, for example in a condenser having small pipe sections, or a small liquid header, be more or less intermittent. In such a case, if the periods of downward flow of the gas were frequent enough, and

sufficiently sustained to keep the condenser 1 relatively free of foreign gases, the device will function with good results.

An important feature of the invention is that the apparatus functions to produce a continuous or substantially continuous discharge of foreign gases from the condenser and their simultaneous accumulation in a part of the system where their presence does not retard the useful heat transfer and therefore. exerts a minimum harmful eflect on the efficiency of the system as a whole. Furthermore, the accumulation of these gases by gravity flow, aided by the general flow of the refrigerant, and their retention by a positively maintained liquid seal, leads to the effective localization of the foreign gases with a consequently highly eflective purging action, and this without the loss of any substantial quantity of refrigerant.

Various changes are possible in the apparatus without departing from the spirit of the invention, and no limitation to the specific structure is implied.

\Vh at is claimed'is:

1. The combination with a refrigerating system including a condenser and a receiver, of a purge chamber interposed, in the refrigerant line leaving the condenser below the bottom of the condenser and in advance of the receiver; a trap arranged to be sealed ber and serving to preclude the passage of gas therefrom; means for cutting said purge chamber out of the system; and means for venting said purge chamber.

3. The combination with a refrigerating system including a condenser, of a purge chamber interposed in the refrigerant line leaving the condenser below the bottom of r the condenser; a trap arranged to be sealed by liquid passing through the purge chamber and servingto preclude the passage of gas therefrom; means for cutting said purge chamber out of the system; means for chilling the contents of said purge chamber sufliciently to liquefy refrigerant gas present therein; and means for venting said purge chamber.

4. The combination with a refrigerating system including a condenser, of a purge chamber interposed in the refrigerant line leaving the condenser below the bottom of the condenser; a trap arranged to be sealed by liquid passing through the purge chamber and serving to preclude the passage of gas therefrom; means for cutting said purge chamber out of the system; means for chilling the contents of said purge chamber sufficiently to liquefy refrigerant gas present therein; means serving to withdraw liquid refrigerant from said purge chamber and to return it to the system while said purge chamber is cut out of the system; and means for venting said purge chamber.

5. The combination with a refrigerating system including a condenser, of a purge chamber interposed in the refrigerant line leaving the condenser below the bottom of the condenser; a trap arranged to be sealed by liquid passing through the purge chamber and serving to preclude the passage of gas therefrom; means for cutting said purge chamber out of the system; means for chilling the contents of said purge chamber sufliciently to liquefy refrigerant gas present therein; an indicating chamber provided with a liquid gauge and means for connecting it with said purge chamber to receive liquid refrigerant therefrom; and means for" venting said purge chamber.

6. The combination with a refrigerating system including a condenser and a liquid receiver; of a purge chamber and a combined oil separator and liquid sealed trap interposed in the order stated in the refrigerant line between the condenser and. the

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liquid receiver; means for cuttin said purge chamber out of the system an venting said purge chamber.

7. The combination with a refrigerating 5 s stem, including a condenser; of a purge chamber-in communication with the refri erant line leading from the condenser, said purge chamber being below the bottom of the condenser; means for forming a liquid trap in the refrigerant line beyond the communication to the purge chamber, said trap serving to obstruct the passage of foreign gas; and means for venting said purge chamber. i

8. The combination with a refrigerating means for chamber.

system, including a condenser; of a purge c amber below the bottom of the condensinand in communication with the refrigerant line leadin from the condenser means for forming a iquid trap in the refrigerant line beyond thecommunication to the purge chamber, said trap serving to obstruct the passage of fOreign gas; means for isolating said pure chamber from the refrigegant 11116 an means for venting said purge In testimony whereof have signed my name to this specification.

TIIOMAS SHIPLEY. 

